Perforator for wells



April v1943- A. BOYNTON 2,315,496

PERFORATOR FOR WELLS Filed Nov. 28, 1938 IIIIIIIIIIIII III I IIIIIII III'I' II II IIII I I I m III III I I IW MIMI! IIIIIIIIMI A rfO/P/VEYS.

l atented Apia race STATES) 3 (Claims.

My invention relates to a means and method of perforating Well casing and of cutting openings through cement and formations of the earth exterior of the casing.

An object is to perforate through the well casing, the cement surrounding the casing, if any,

and penetrate the adjacent productive formations of earth strata in order to admit into the well whatever production such formations may bear.

Another object is to cut in two casing, liners or other pipe in wells, in order that the upper portion so cut ofi can be recovered.

A further object is to free or destroy tools or other objects stuck or lost in wells, in order that such wells may be cleaned and saved.

A still further object is to provide increased storage reservoirs in wells which reservoirs will allow large accumulationsof well fluid therein, in order that the static head of well liquid will he kept relatively low while the volume of well fluid available for periodic pumping after such accumulation will be relatively great,

The recent trend toward drilling wells, particularly oil and gas wells, then setting casing and cementing around it; thereby excluding from the casing all production in the adjacent earth formations, renders some elicient means of cutting through the casing and penetrating the productive formations very important.

The present practice of gun perforating the casing, surrounding cement, and formations beyond, is adapted to puncture the casing, cement, andothcrformations with relatively small openings, usually to /8" in diameter. The diam eter of such gun perforations is practically constant, but, due to the decreasing velocity of the bullets discharged from such guns, the fracture zone around'the bullet holes decreases as the bullets penetrate further into such formations. One of the principal objects of this invention is, not only to penetrate further than bullets can be tired, but to produce openings of increasing diameter at progressively greater distances from. the wells.

One of the most destructive agencies in the rotary method of drilling wells is the abrasive action of sand and other hard particles in the drilling fluid which cuts out the holes in bits, destroys tool joints. and fittings. This destructive agency is employed for a useful purpose in this invention by adding sharp sand; emery grains, particles of adamantine, or the like, to the drilling fluid; thereby making the fluid much more abrasive;

and then discharging it under great pressure through nozzles directed against the well cement surrounding'it, and formations extericr thereof.

I attain these and other objects by mechanism illustrated in the accompanying drawing,

which- Fig. l is a longitudinal section through the per forator assembly.

Fig. 2 is a transverse section on the line 2-2, Fi 1.

Fig. 3 is a longitudinal section through the ele vice in operation and the lower portion of the drill stem or tubing through which the pump fluid is supplied; the well casing, surrounding cement, and adjacent formations being also shown in longitudinal section. I

Similar reference numerals and letters refer to similar parts throughout the several views.

In Fig. l nipple l, having threaded connection to drill pipe or tubing 5 (see Fig. 3), by means of coupling 6 (also appearing in Fig. 3 only), has a plurality of nozzle t spaced at intervals in opposite sides or nipple 6.. Those nozzles are shown to be threadedly engaged through the wall of nipple l, and may be so engaged or disengaged by use oi a pin wrench which may be applied by means of pin holes 21). The central longitudinal opening 2a of each nozzle preferably, tapered,

through each nozzle will be free and unobstructed I by the casing 'i (see Fig. 3), when the pump is started at beginning of the perforating operation.

The guide plug 3, having guide fins to, has threaded connection into the lower end of nipple i. The ball check valve 6, adapted to engage the valve seat 30, has ample clearance to pass between the wall of nipple l and the nozzles 2, because,

' preferably, the ball is dropped into the pipe or tubing after the device has been lowered to oper ating position. This is so, because it is desirable that the opening 311 should be left open while the pipe or tubing is being run into the well, in order that mud or settlings can be washed out by the pump before the cutting stream is directed through the nozzles, which might otherwise hecome choked by such mud or settlings.

In operation, the device is lowered into the casing to the place where it is desired to per-= forate, and allowed to hang suspended, as illustrated in Fig. 3.. The pump is then started and run until free circulation of the mud or muddy water of uniform specific gravity is obtained; the circulation path being, of course, downward in the drill pipe or tubing 5 and upward to the ground surface through the annular space M. Sharp sand, emery grains, adamantine particles or the like, or a suitable blend of such substances, is now mixed into the pump fiuid'until a highly abrasive mixture is obtained. Baroid, or any other substance adapted to increase specific gravity, may be added to the pump fluid to assist in holding the abrasive substances in suspension. When the pump fluid has been charged with enough abrasives to cut rapidly, care being taken to not overload the mud with such substances until it will choke the discharge openings 2a of the nozzles, the ball checl; valve 6, which may be of steel, is dropped into the drill pipe or tubing. When the ball engages the seat 30 all of the pump fiuidis thereby diverted through the openings 2a. In this manner the casing will be quickly perforated. Soon thereafter the cement ii will be out through, and

the formation exterior thereof abraded away for considerable distance. During this operation the cutting fluid doubles back from the point of impact with the cement or formation, passing around the outgoing stream and circulates back to the pump pit, where the fluid is tested, from time to time-and reconditioned as necessary.

If the pump or pumps supply a steady pressure, the opening through the casing, cement, and formation will be approximately cone shaped with the small end of the cone focused at the casing. pump be employed to impart intermittent pressure to the cutting fluid, the pipe or tubing will be elongated at each impulse of the pump and contract to normal length at each cessation of the pump impulse. Consequently, the opening through the casing will be slot shaped, as indicated at Q, and the opening through the cement recent trend to the use of high steam pressures in rotary drilling. furthermore lends itself to the employment of high pump pressures desirable for this type of cutting.

If, however, a single cylinder Ii it is desired to cut the casing l in two, preferably only one nozzle is used, and the pipe or tubing 5 is rotated slowly during the cutting operation.

If it is desired to free or destroy a lost tool or other substance lost in the well the jets may be removed from the side of nipple i and the opening 3b in guide plug 3 may be transformed into a nozzle pointing downward or at any necessary angle to direct the abrading stream upon the object .to be freed or destroyed.

Manifestly, many minor changes in construction can be made within the scope and purpose of the stated objects and appended claims; and I reserve the right to make such changes.

Having thus set out and described my invention, I claim:

l. A method of perforating casing comprising the steps of lowering a pipe string into the casing to be perforated, circulating liquid through the string and surrounding annular space until uniform specific gravity of the liquid- 2. H well perforating device comprising a tubular member extending down into the well to the iarea to be perforated, means for closing the lower end of the member'against downward how of liquid therethrough after the member is lowered to a predetermined level in the well, and nozzles in said member opening outwardly therefrom to direct against localized areas of the casing and adjacent formation an abradin liquid pumped downwardly within the tubular member.

imum nozzling effect is obtained and a maximum acceleration imported to said abrading fluid in the limited space available.

1 I BOYNTON. 

